neděle 8. ledna 2012

Adaptive infill

After hours and hours of
watching our reprap at http://brmlab.cz two things come to my mind –
first, skeinforge's standard infill pattern is way prettier than any
of slic3r's and second - and more important - that none of the infill strategies actually take
advantage of the models shape. After reading
http://garyhodgson.com/reprap/2012/01/thoughts-on-fill-algorithms/, I decided to write my thoughts on how I think it should be done:

First, divide sliced
object into cubes one layer high and for example three extrusion
widths in remainig directions (this equals to 33% infill), then count
how far is each cube from nearest surface (in all 3 dimensions).
Divide cubes into regions, depending on how deep inside the object
cubes are. In pictures here you can see 3 regions,[1-2], [3-6],[7-14 which I was too lazy to mark with numbers]

Infill density is then
dictated by region, every region border will halve the density:

Next layer is then done
same way, but rotated as usual:

Infill that stays in region 1 can then be
extruded with lower flowrate (thinner) saving material and lines
crossing higher groups can be made increasingly thicker, for really
strong internal support. All this should assure that we have strong
infill that supports ceilings well, but without using much material.
This model can be developed further, for example cubes may be more
layers high, making infill be naturally more layers thick – this is
similar to what skeinforge does in “skin” plug-in, but as its
done by grouping layers and not dividing, it will bring better
results. EDIT: Slic3r can already do this with infill_every_layers option.